Help Adding an Activity Indicator on a tab bar application!

Please I need help. I have a tab bar app, and need to put an activity indicator. It doesn't work through the actual view controller. As a little background info, i have five view controller, each corresponding to a tab in a tab bar. They all have UIWebViews and I want an activity indicator to be displayed while they load. But, nothing I tried works. I think I should put the code in the app delegate, but the code I used didn't work, hope someone can help me, or give me the code for the app delegate activity indicator.
Thanks in advance!

 

Yep, it's the latter!

 

What section of the code do I use?